Washing machine and method of controlling rinsing cycle

ABSTRACT

A washing machine capable of optimizing the rinsing time and the amount of rinsing water by using a conductivity sensor, and a method of controlling a rinsing cycle thereof. When the amount of detergent remaining in the rinsing water is determined to be small according to the measured conductivity, the amount of rinsing water and the rinsing time are minimized, that is, the rinsing water is alternately supplied in stages of times, the conductivity of the rinsing water is measured at the stop of the supply of rinsing water, and if the measured conductivity is below a reference value, the rinsing cycle is stopped and enters to a final-spin dry cycle, so that the water and energy is saved and the rinsing is achieved with the optimum algorithm when laundry having a little contamination and a small amount of detergent is input.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Korean PatentApplication No. 10-2011-0131272, filed on Dec. 8, 2011 in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference.

BACKGROUND

1. Field

The following description relates to a washing machine capable ofoptimizing the rinsing time and the amount of rinsing water by using aconductivity sensor, and a method of controlling the rinsing cyclethereof.

2. Description of the Related Art

In general, a washing machine for example, a drum-type washing machine,is an apparatus including a water tub to store water, for example,washing water or rinsing water, a cylindrical drum rotatably installedin the water tub to receive laundry, and a motor to generate a drivingforce to rotate the drum. As the cylindrical drum rotates, the laundryaccommodated in the drum is ascended and descended, so the laundry iswashed by the descending force.

The washing machine proceeds with washing by performing a series ofoperations including a washing cycle to separate dirt from the laundryby using water (i. e., wash water) having detergent dissolved therein, arinsing cycle to rinsing bubbles or remaining detergent from the laundryby using water (i. e., rinsing water) that does not include detergent,and a spin-dry cycle to spin-dry the laundry at a high speed. During therinsing cycle, water (i.e., rinsing water) is supplied, and the drum isalternately rotated during a predetermined time to force the suppliedwater to make contact with the laundry and then to be descended, so thatthe laundry is rinsed by the descending force. The rinsing cycle isperformed in a predetermined number of times (or a user-selected numberof times) with a predetermined rinsing time and a predetermined amountof rinsing water that are determined according to the weight (load) ofthe laundry.

However, in the case of laundry having a little contamination, a usermay put a small amount of detergent according to the weight of thelaundry. According to the conventional washing machine, the rinsingcycle is performed by a predetermined number of times with apredetermined rinsing time and a predetermined amount of rinsing waterthat are determined according to the weight (load) of laundry regardlessof the amount of detergent that is input in the washing machine.Accordingly, even when the rinsing cycle is needed to be finished due tothe depletion of detergent dissolved in the rinsing water, the rinsingcycle is continued, thereby causing water and energy to be wasted.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide awashing machine implementing an algorithm capable of measuring theconductivity of rinsing water by using a conductivity sensor andminimizing the rinsing time and the amount of rinsing water ifdetermined that the amount of detergent dissolved in the rinsing wateris small according to the measured conductivity, and a method ofcontrolling the rinsing cycle thereof.

Additional aspects of the disclosure will be set forth in part in thedescription which follows and, in part, will be apparent from thedescription, or may be learned by practice of the disclosure.

In accordance with one aspect of the present disclosure, a method ofcontrolling a washing machine provided with a drum, a water tubinstalled outside the drum to receive rinsing water and a motor torotate the drum is as follows. Rinsing water may be supplied in astepwise manner. A rinsing cycle may be performed by alternatelyrotating the drum according to a drive of the motor during the supplyingof rinsing water in a stepwise manner. A conductivity of the rinsingwater may be measured during the performing of the rinsing cycle. Arinsing profile of the rinsing cycle may be changed according to themeasured conductivity of the rinsing water.

The supplying of rinsing water in a stepwise manner may includesupplying the rinsing water for a first time that is set to measure theconductivity of the rinsing water, and supplying the rinsing water for atime that is set in stages to adjust an amount of supply of the rinsingwater according to the measured conductivity.

The first time may be a time configured to supply a minimum amount ofrinsing water required to measure the conductivity of the rinsing water.

The time set in stages may be a time configured to supply an amount ofrinsing water suitable to adjust the amount of supply of the rinsingwater.

The amount of supply of the rinsing water may be adjusted to be inproportion to the measured conductivity.

If the conductivity is large, the amount of supply of the rinsing watermay be increased so that the conductivity of the rinsing water israpidly lowered.

The rinsing cycle may perform an alternate supply of water in which thedrum is alternately rotated whenever the rinsing water is supplied in astepwise manner.

In the measuring of the conductivity of the rinsing water, theconductivity of the rinsing water may be measured when the alternatesupply of water is stopped.

The rinsing profile may compare the measured conductivity of the rinsingwater with a reference value, and finish the rinsing cycle that isperformed through the alternate supply of water if the measuredconductivity is below the reference value.

The rinsing profile may compare the measured conductivity of the rinsingwater with a reference value, and control the rinsing cycle that isperformed through the alternate supply of water if the measuredconductivity is greater than or equal to the reference value.

In the rinsing cycle performed through the alternate supply of water,rinsing water may be supplied while adjusting the amount of supply ofrinsing water according to the measured conductivity, and an alternatesupply of water is performed in which the drum is alternately rotatedwhen the rinsing water is supplied.

The amount of supply of the rinsing water may be adjusted by supplyingrinsing water for the time that is set according to the measuredconductivity.

If the measured conductivity is higher, the time set to supply rinsingwater may be larger such that a larger amount of the rinsing water issupplied.

The amount of supply of the rinsing water may be adjusted by supplyingrinsing water to a water level that is set according to the measuredconductivity.

If the measured conductivity is higher, the water level set to supplyrinsing water may be larger such that a larger amount of the rinsingwater is supplied.

In accordance with another aspect of the present disclosure, a washingmachine includes a water tub, a water supply apparatus, a conductivitysensor and a control part. The water supply apparatus may be configuredto supply the water tub with rinsing water. The conductivity sensor maybe configured to measure a conductivity of the rinsing water. Thecontrol part, at a rinsing cycle, may be configured to supply the watertub with the rinsing water in a stepwise manner by controlling the watersupply apparatus, and may change a rinsing profile of the rinsing cycleaccording to the conductivity of the rinsing water that is measured bythe conductivity sensor.

The water supply apparatus may supply the rinsing water in a stepwisemanner according to a control of the control part. The water supplyapparatus may supply the rinsing water for a first time that is set inthe control part so as to measure the conductivity of the rinsing water,and supply the rinsing water for a time that is set in stages in thecontrol part so as to adjust an amount of supply of the rinsing wateraccording to the measured conductivity.

The control part may adjust the amount of supply of the rinsing water tobe in proportion to the measured conductivity.

The control part may control, if the conductivity is large, the amountof supply of the rinsing water is increased so that the conductivity ofthe rinsing water is rapidly lowered.

The washing machine may further include a motor to rotate the drum. Thecontrol part may perform the rinsing cycle by alternately rotating thedrum according to the driving of the motor during the alternate supplyof water.

The conductivity sensor may measure a conductivity of the rinsing waterthat is changed through the alternate supply of water.

The control part may include the measured conductivity of the rinsingwater with a reference value, and if the measured conductivity is belowthe reference value, change the rinsing profile to finish the rinsingcycle that is performed through the alternate supply of water.

The control part may compare the measured conductivity of the rinsingwater with a reference value, and if the measured conductivity isgreater than or equal to the reference value, change the rinsing profileto control the rinsing cycle that is performed through the alternatesupply of water.

The control part may control the water supply apparatus to adjust anamount of supply of the rinsing water according to the measuredconductivity.

The control part may adjust the amount of supply of the rinsing waterduring a time that is set according to the measured conductivity.

The control part, if the measured conductivity is higher, may controlthe time, which is set to supply the rinsing water, to be larger suchthat a larger amount of the rinsing water is supplied.

The control part may adjust the amount of supply of the rinsing water toa water level that is set according to the measured conductivity.

If the measured conductivity is higher, the water level may be set to belarger such that a larger amount of the rinsing water is supplied.

As described above, a washing machine and a method of controlling therinsing cycle thereof implement an algorithm in which the conductivityof rinsing water is measured by using a conductivity sensor at a rinsingcycle, the amount of detergent dissolved in the rinsing water isdetermined according to the measured conductivity, and the amount ofrinsing water and the rinsing time are minimized if determined that theamount of detergent is small, so that water and energy are saved. Duringthe rinsing cycle, the algorithm for minimizing the rinsing time and theamount of rinsing water measures the conductivity of rinsing water whilesupplying the rinsing water in a stepwise manner, and controls theamount of rinsing water and the rinsing time. That is, the alternatesupply of rinsing water is performed according to the stages of time atthe supplying of the rinsing water, and the conductivity of rinsingwater is measured at the stopping of the water supply, so that therinsing cycle is stopped, and a final spin-dry cycle is performed if themeasured conductivity is below a predetermined value. Accordingly, whena laundry having a little contamination is needed to be washed, and asmall amount of detergent is input, the rinsing performance is obtainedwith the optimum algorithm without wasting the water and energy.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the disclosure will become apparent andmore readily appreciated from the following description of embodiments,taken in conjunction with the accompanying drawings of which:

FIG. 1 is a perspective view illustrating the external appearance of awashing machine in accordance with an embodiment of the presentdisclosure.

FIG. 2 is a cross-sectional view illustrating the configuration of thewashing machine in accordance with an embodiment of the presentdisclosure.

FIG. 3 is a view illustrating an operational concept of a conductivesensor in accordance with an embodiment of the present disclosure.

FIG. 4 is a view illustrating a control block diagram of the washingmachine in accordance with an embodiment of the present disclosure.

FIG. 5 is a flowchart illustrating a control operation sequence of arinsing cycle of the washing machine in accordance with an embodiment ofthe present disclosure.

FIG. 6 is a flow chart illustrating an operation sequence of a stepwiserinsing profile of the washing machine in accordance with an embodimentof the present disclosure.

FIG. 7 is a flow chart illustrating a control operation sequence of arinsing cycle of a washing machine in accordance with another embodimentof the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout.

FIG. 1 is a perspective view illustrating the external appearance of awashing machine in accordance with an embodiment of the presentdisclosure. FIG. 2 is a cross-sectional view illustrating theconfiguration of the washing machine in accordance with an embodiment ofthe present disclosure.

Referring to FIGS. 1 and 2, a washing machine 1 in accordance with anembodiment of the present disclose includes a body 10 provided in a boxshape forming an external appearance of the washing machine 1, a watertub 11 installed at an inside the body 10 and provided in a drum type toreceive water (washing water or rinsing water), and a drum 12 rotatablyinstalled inside the water tub 11 and provided with a plurality of holes13.

A motor 15, as a driving apparatus, is installed at the outer side of arear surface of the water tub 11 so as to rotate a rotary shaft 15 a,which is connected to the drum 12 to perform a washing cycle, a rinsingcycle, and a spin-dry cycle.

In general, the motor 15 is implemented using a universal motor composedby including a field coil and an armature, or a brushless direct motor(BLDC) motor composed by including a permanent magnet and an electricmagnet. However, the motor 15 in accordance with the present disclosureis not limited thereto, and other motors applicable to a small-to-mediumsized drum, such as the drum 12, may be used as the motor 15.

A water level sensor 16 is installed at a lower side of the inside thewater tub 11 to detect a frequency that varies with the water level todetect the amount of water (i.e., water level) of the water tub 11, awashing heater 17 to heat the water in the water tub 11, and aconductivity sensor 18 or a turbidity sensor to detect the conductivityof water, in detail, the conductivity of rinsing water in the water tub11.

In addition, the body 10 is provided at a front surface thereof with adoor 19 having an inlet 19 a through which a laundry is input orwithdrawn into/from the drum 12.

A detergent input apparatus 20 to supply detergent, for example,synthetic detergent or natural soup, and a water supply apparatus 30 tosupply water (washing water or rinsing water) are installed on the upperside of the water tub 11.

The detergent input apparatus 20 has an interior divided into aplurality of spaces, and is installed at a front surface side of thebody 10 to facilitate the input of the detergent and the fabricsoftener.

In addition, the water supply apparatus 30 includes a cold water supplypipe 31 and a hot water supply pipe 32 to connect between an outsidewater supply pipe and the detergent input apparatus 20 to supply water(washing water or rinsing water) into the water tub 11, a cold watervalve 33 and a hot water valve 34 installed in the middle of the coldwater supply pipe 31 and the hot water supply pipe 32, respectively, tocontrol the supply of water, and a connection pipe 35 to connect betweenthe detergent input apparatus 20 and the water tub 11. Through theconfiguration as such, the water introduced into the water tub 11 passesthrough the detergent input apparatus 20, so that the detergent in thedetergent input apparatus 20 is supplied to the water tub 11 togetherwith water.

In addition, a control panel 40, on which various buttons and a displaypart are disposed to control the washing machine 1, is provided on theupper side of the front surface of the body 10. A detergent input part21 is provided at one side of the control panel 40 while being connectedto the detergent input apparatus 20 so as to input the detergent for thewashing machine 1.

The control panel has the various buttons to receive a command by a userfor controlling an operation of the washing machine 1, and the displaypart to display an operation state of the washing machine 1 and amanipulation state of the user.

In addition, the washing machine 1 in accordance with the presentdisclosure is provided with a drain apparatus 50 installed thereto todrain the water in the water tub 11. The drain apparatus 50 includes afirst drain pipe 51 connected to a lower portion of the water tub 11 todrain the water in the water tub 11 to an outside, a drain pump 52installed on the first drain pipe 51, and a second drain pipe 53connected to an exit of the drain pump 52.

In addition, the washing machine 1 in accordance with the presentdisclosure is provided with a suspension spring 60 to elasticallysupport the water tub 11 at the upper side of the water tub 11 and witha damper 62 to reduce the vibration at the lower side of the water tub11, thereby preventing the vibration from being generated during theoperation of the washing machine 1.

The suspension spring 60 and the damper 62 movably support the water tub11 at the upper side and the lower side, respectively. That is, as thedrum 12 rotates, the water tub 11 is excited by a vibration excitationforce generated due to the rotation of the drum 12, and is vibrated inbackward/forward, left/right and upward/downward directions. Such avibration in all directions is reduced by the suspension spring 60 andthe damper 62.

FIG. 3 is a view illustrating an operational concept of a conductivesensor in accordance with an embodiment of the present disclosure.

Referring to FIG. 3, the conductivity sensor 18 may be composed by aplurality of electrodes 18 a and 18 b that are disposed while beingspaced apart from each other in a predetermined interval. Alternatively,the conductivity sensor 18 may be composed by one electrode whilegrounding an inner metal part of the washing machine 1. In this case,each of the ground and the one electrode serves as an electrode, andprovides the same characteristic as in the measuring of the conductivityof water (i.e., rinsing water) through the change in a capacitance (C)between the two electrodes 18 a and 18 b that are spaced apart from eachother in a predetermined interval.

As described above, the conductivity of water making contact withbetween the plurality of electrodes 18 a and 18 b, that is, theconductivity varying with the amount of detergent dissolved in therinsing water is detected by using the capacitance (C), so that thedegree of residual detergent in the rinsing water during the rinsingcycle is detected. In this case, if a greater amount of detergent isinput in the water, the conductivity is increased according to theionization of the detergent.

FIG. 4 is a view illustrating a control block diagram of the washingmachine in accordance with an embodiment of the present disclosure.

Referring to FIG. 4, the washing machine 1 includes an input part 70, acontrol part 72, a memory 73, a driving part 74, and a display part 76.

The input part 70 is configured to enter commands to execute the washingcycle, the rinsing cycle and the spin-dry cycle of the washing machine 1according to the manipulation of a user. The input part 70 includes akey, a button, a switch, and a touch pad, and may further include otherapparatuses capable of generating a predetermined input data accordingto the pressing, the contacting, the pressurizing and the rotatingmanipulations.

In addition, the input part 70 is provided on the control panel 40, andincludes a plurality of buttons to enter a command of a user with regardto the operation of the washing machine 1, for example, with regard tothe power-on/off, reservation, the temperature of wash water, soaking,washing, rinsing, spin-drying, and the type of detergent.

In addition, the input part 70 is provided with an eco-rinsing button 71to select a rinsing cycle to wash the laundry that has a littlecontamination.

The eco-rinsing button 71 is additionally provided on the control panel40 to change an algorithm of the rinsing cycle to adapt to the amount ofthe detergent input when the laundry having a little contamination isneeded to be washed, and a user inputs a smaller amount of detergentrelative to the weight of the laundry.

The control part 72 represents a microcomputer to control the overalloperation of the washing machine 1, such as the washing, the rinsing,and the spin-drying, according to the operation information that isinput from the input part 70. The control part 72 sets the amount ofwashing water, the amount of rinsing water, the target RPM, the motoroperation rate (motor on-off time), the time to wash and the time torinse according to the weight (load) of the laundry at a selectedwashing course.

In addition, the control part 72, at the rinsing cycle, measures theconductivity of the rinsing water by using the conductivity sensor 18,and determines the amount of detergent dissolved in the rinsing wateraccording to the measured conductivity. As a result of thedetermination, if determined that the amount of detergent dissolved inthe rinsing water is small, the control part 72 implements an algorithmto minimize the time to rinse and the amount of rinsing water to savethe water and the energy.

The algorithm to minimize the time to rinse and the amount of rinsingwater is to control the amount of rinsing water and the time to rinse bymeasuring the conductivity of the rinsing water while supplying therinsing water in a stepwise manner, other than to proceed a rinsingcycle in a predetermined number of times with a predetermined rinsingtime and a predetermined amount of rinsing water that are determinedaccording to the weight (load) of the laundry.

In detail, when the rinsing is started, rinsing water is alternatelysupplied in stages of time. At the completion of the alternate supply ofrinsing water, the conductivity of the rinsing water is measured in astate that the supply of the rinsing water is stopped, and if themeasured conductivity is below a predetermined value, the rinsing cycleis finished and the spin-dry cycle is proceeded. In this manner, thewashing operation is achieved with the optimum algorithm without wastingthe water and energy in a case where a small amount of detergent isinput to wash the laundry having a little contamination.

As described above, when a small amount of detergent is input to washthe laundry having a little contamination, the present disclosureimplements an algorithm to minimize the amount of rinsing water and thetime to rinse according to the conductivity of the rinsing water withouthaving to select an additional button. In addition, by selecting theeco-rinsing button 71 provided on the control panel 40, the algorithm tominimize the amount of rinsing water and the rinsing time may beselected for implementation.

In addition, the memory 73 may store control data to control theoperation of the washing machine 1, reference data available for useduring the control of the operation of the washing machine 1, operationdata that is generated during the execution of a predetermined operationof the washing machine 1, setting information that is input by the inputpart 70 such that the washing machine 1 performs a predeterminedoperation, for example, setting data, the number of times by which thewashing machine 1 has performed a predetermined operation, usageinformation including model information of the washing machine 1, andmalfunction information including the cause and the location oferroneous operation of the washing machine

The driving part 74 drives the motor 16, the washing heater 17, the coldwater valve 33, the hot water valve 34, and the drain pump 52 related tothe operation of the washing machine 1 according to a driving controlsignal of the control part 72.

The display part 76 is provided on the control panel 40, and displaysthe operation state of the washing machine 1 and the manipulation stateof the user according to a display control signal of the control part72.

Hereinafter, the washing machine in accordance with an embodiment of thepresent disclosure, the operation of the control method of the rinsingcycle thereof, and the operational effect thereof will be described.

FIG. 5 is a flow chart illustrating a control operation sequence of arinsing cycle of the washing machine in accordance with an embodiment ofthe present disclosure.

An embodiment of the present disclosure is described in relation to arinsing cycle in which a rinsing profile is changed with an algorithmoptimized for a case where the laundry having a little contamination isneeded to be washed and a small amount of detergent is input.

Referring to FIG. 5, laundry, for example, the bed sheet, having alittle contamination is input into the inside the drum 12, and a smallamount of detergent is input into the detergent input apparatus 20. Asthe operation information related to a washing course, for example, acourse for the bed sheet, and the operation of the washing machine 1 isinput by a user according to the type of the laundry, the operationinformation selected by the user is input into the control part 72through the input part 70.

The control part 72 starts to wash and rinse the laundry according tothe operation information input from the input part 70.

The control part 72 detects the weight (load) of the laundry input intothe drum 12 so as to proceed with the washing and the rinsing (100). Theweight detection may be achieved by using the time taken for a motor toreach a predetermined speed or a predetermined revolution per minute(RPM) after the motor 15 performs an instantaneous acceleration.Alternatively, the weight detection may be achieved by directly orindirectly measuring the moment of inertia of the drum 12 in a statethat a torque is applied to a motor in a predetermined period of timeand by using Newton's second law (see Japanese unexamined patentpublication No. 2002-336593, Japanese unexamined patent publication No.2004-267334 and Japanese unexamined patent publication No. Hei07-90077).

However, the present disclosure is not limited thereto. For example, theweight detection may be achieved through a generally known scheme usinga load cell.

If the weight (load) of the laundry is detected, the control part 72sets the amount of washing water, the amount of rinsing water, thetarget RPM, the motor operation rate (motor on-off time), and thewashing time and the rinsing time according to the detected weight(load) of the laundry.

Thereafter, the control part 72 operates the cold water valve 33 or thehot water valve 34 to supply the water required for the washing cycle.

As the cold water valve 33 and the hot water valve 34 operate, the coldwater valve 33 or the hot water valve 34 is open, and the water (washingwater), which is supplied from the outside a water supply pipe afterpassing through the cold water supply pipe 31 or the hot water supplypipe 32, the detergent input apparatus 20, and the connection pipe 35,is supplied to the inside the water tub 11, in detail, a space betweenthe water tub 11 and the drum 12, together with the detergent (102).

Accordingly, the control part 72 determines whether a current waterlevel corresponds to a target washing water level, which is determinedaccording to a designated amount of washing water, by detecting thewater level of the water being supplied to the water tub 11 through thewater level sensor 16, and keeps supplying water until the water levelof the water being supplied to the water tub 11 reaches the targetwashing water level.

If the supplying of washing water to the target washing water level iscompleted, the control part 72 operates the motor 15 at the target RPMand at the operation rate (motor on-off time), which are set for thewashing cycle, to alternately rotate the drum 12, so that the washingcycle is performed while generating a water current to transportdetergent water including washing water and detergent to the laundry(104).

If the washing for a designated washing time is completed, the controlpart 72 stops the drum 12 and drains the detergent water (106), andproceeds with an interim spin-dry (108).

Thereafter, the control part 72 starts supplying water (rinsing water)required for the rinsing cycle to perform the rinsing cycle. The supplyof the rinsing water is performed in a different manner from the supplyof the washing water.

According to the present disclosure, the user inputs a small amount ofdetergent required to wash the laundry having a little contamination, sothe amount of detergent remaining in the water tub 11, after washing iscompleted, is smaller than the amount of detergent that remains afterthe washing is performed by automatically inputting the detergentaccording to the weight (load) of the laundry.

Based on the point that the rinsing does not need to be performed in apredetermined number of times with a predetermined amount of rinsingwater and in a predetermined rinsing time that are set according to theweight of the laundry, the present disclosure implements a rinsingprofile capable of minimizing the amount of rinsing water and therinsing time.

According to the rinsing profile to minimize the amount of rinsing waterand the rinsing time, rinsing water is alternately supplied by stages oftime at the start of the supply of rinsing water, and the conductivityof the rinsing water is measured at the stop of the supply of rinsingwater such that the rinsing cycle is finished to enter to a finalspin-dry cycle if the measured conductivity is below a reference value.Hereinafter, the rinsing profile will be described in detail.

If the supply of the rinsing water is started, the control part 72alternately supplies rinsing water such that a minimum amount of rinsingwater required to measure the conductivity of the rinsing water issupplied (110). The alternate supply of rinsing water is achieved as thecontrol part 72 alternately rotates the drum 12 when the cold watervalve 33 or the hot water valve 34 is open according to the operation ofthe water supply apparatus 30 and water (rinsing water) is supplied tothe inside the water tub 11 to make contact with the laundry such thatthe rinsing is performed by a descending force of the rinsing waterafter making contact with the laundry.

In the alternate supply of rinsing water, a first amount of water, forexample, the minimum amount of rinsing water corresponding to the weightof laundry of about 1 kg, which is required to measure the conductivityof the rinsing water, is needed to be supplied.

To this end, the control part 72 counts the number of times during whichrinsing water is alternately supplied, and determines whether apredetermined first time, which is the time to supply the minimum amountof rinsing water required to measure the conductivity of the rinsingwater, for example, about 10 seconds is elapsed (112).

As a result of the determination in operation 112, if determined thatthe first time is elapsed, the control part 72 stops the alternatesupply of rinsing water (114), and measures the conductivity of therinsing water by using the conductivity sensor 18. The measuring of theconductivity of the rinsing water is achieved at a time when thealternate supply of rinsing water is stopped, that is, at an off-time ofthe motor operation rate (motor on-off time), and the conductivitymeasured at this time is input to the control part 72 (116).

Accordingly, the control part 72 compares the measured conductivity witha reference conductivity (X; the conductivity of having almost nodetergent in the rinsing water, the conductivity having a level of about250 μs/cm, hereinafter, referred to as a reference value), anddetermines whether the measured conductivity is below the referencevalue X (118).

As a result of the determination in operation 118, if determined thatthe measured conductivity is below the reference value X, the controlpart 72 determines that almost no detergent remains in the rinsingwater, and thus drains the rinsing water without proceeding with therinsing cycle (120).

After the rinsing water is drained, the control part 72 performs aspin-dry cycle at a final spin-dry RPM, at about 1100 RPM or above(122), and stops the drum 12, completing all cycles.

As described above, the conductivity of the rinsing water is measuredduring the rinsing cycle, and if the measured conductivity is below thereference value X, the rinsing cycle is finished, and then enters to thefinal spin-dry cycle, so that the rinsing operation is achieved with theoptimum algorithm without wasting the water and the energy.

As a result of the determination in operation 118, when the measuredconductivity is not below the reference value X, the control part 72determines that detergent remains in the rinsing water, and proceedswith a rinsing profile to control the amount of rinsing water and therinsing time while supplying the rinsing water in stages according tothe measured conductivity. Since the higher the conductivity detected bythe conductivity sensor 18 is, the more detergent remains in the rinsingwater, the rinsing profile is to adjust the amount of rinsing water,which is to be supplied at a next stage of time, to reduce the rinsingtime while saving the amount of rinsing water. The rinsing profile isdescribed with reference to FIG. 6.

FIG. 6 is a flow chart illustrating an operation sequence of a stepwiserinsing profile of the washing machine in accordance with an embodimentof the present disclosure. FIG. 6 illustrates a rinsing profile tocontrol the amount of rinsing water and the rinsing time while supplyingrinsing water in stages of time according to the conductivity measuredin FIG. 5.

In FIG. 6, the control part 72 compares the measured conductivity with apredetermined second conductivity (Y; the conductivity of having a largeamount of detergent in the rinsing water, about 1000 μs/cm or above),and determines whether the measured conductivity is greater than orequal to the second conductivity Y (202).

As a result of the determination in operation 202, if the measuredconductivity is greater than or equal to the second conductivity Y, thecontrol part 72 determines that the amount of detergent remaining in therinsing water is significantly large, and alternately supplies rinsingwater by a second amount of water, which is the maximum amount ofrinsing water suitable to remove the detergent remaining in the rinsingwater in a rapid manner (204). The alternate supply of rinsing water isachieved as the control part 72 alternately rotates the drum 12 when thecold water valve 33 or the hot water valve 34 is open according to theoperation of the water supply apparatus 30 and water (rinsing water) issupplied to the inside the water tub 11 to make contact with the laundrysuch that the rinsing is performed by a descending force of the rinsingwater after making contact with the laundry.

In this case, the control part 72 counts the number of times duringwhich rinsing water is alternately supplied, and determines whether apredetermined second time, which is the time to supply the maximumamount of rinsing water required to rapidly lower the conductivity ofthe rinsing water, for example, about 30 seconds, is elapsed (206).

As a result of the determination in operation 206, if determined thatthe second time is elapsed, the control part 72 stops the alternatesupply of rinsing water (208), and measures the conductivity of therinsing water by using the conductivity sensor 18. Thereafter, themeasured conductivity is input to the control part 72 (210).

Accordingly, the control part 72 provides a feedback to the operation118 to determine whether the measured conductivity is dropped below thereference value X after the rinsing operation is performed through thestepwise supply of rinsing water in an alternating manner.

Meanwhile, as a result of the determination in operation 202, if themeasured conductivity is not greater than or equal to the secondconductivity Y, the control part 72 compares the measured conductivitywith a third conductivity (Y/2; the conductivity of having detergent inthe rinsing water to some extent, about 500 μs/cm or above), anddetermines whether the measured conductivity is greater than or equal tothe third conductivity Y/2 (212).

As a result of the determination in operation 212, if the measuredconductivity is greater than or equal to the third conductivity Y/2, thecontrol part 72 determines that detergent remains in the rinsing waterto some extent, and alternately supplies rinsing water to supply rinsingwater by a third amount of rinsing water, which is the amount of rinsingwater suitable to remove the detergent remaining in the rinsing water(214). The alternate supply of rinsing water is achieved as the controlpart 72 alternately rotates the drum 12 when the cold water valve 33 orthe hot water valve 34 is open according to the operation of the watersupply apparatus 30 and water (rinsing water) is supplied to the insidethe water tub 11 to make contact with the laundry such that the rinsingis performed by a descending force of the rinsing water after makingcontact with the laundry.

In this case, the control part 72 counts the number of times duringwhich rinsing water is alternately supplied, and determines whether apredetermined third time, which is the time to supply the amount ofrinsing water required to lower the conductivity of the rinsing water,for example, about 15 seconds, is elapsed (216).

As a result of the determination in operation 216, if determined thatthe third time is elapsed, the control part 72 stops the alternatesupply of rinsing water (218), and measures the conductivity of therinsing water by using the conductivity sensor 18. Thereafter, themeasured conductivity is input to the control part 72 (220).

Accordingly, the control part 72 provides a feedback to the operation118 to determine whether the measured conductivity is dropped below thereference value X after the rinsing operation is performed through thestepwise supply of rinsing water in an alternate manner.

Meanwhile, as a result of the determination in operation 212, if themeasured conductivity is not greater than or equal to the thirdconductivity Y/2, the control part 72 compares the measured conductivitywith a fourth conductivity (Y/3; the conductivity of having detergent inthe rinsing water to a small extent, about 250 μs/cm or above), anddetermines whether the measured conductivity is greater than or equal tothe fourth conductivity Y/3 (222).

As a result of the determination in operation 222, if the measuredconductivity is greater than or equal to the fourth conductivity Y/3,the control part 72 determines that detergent remains in the rinsingwater to a small extent, and alternately supplies rinsing water tosupply rinsing water by a fourth amount of rinsing water, which is theamount of rinsing water suitable to remove the detergent remaining inthe rinsing water (224). The alternate supply of rinsing water isachieved as the control part 72 alternately rotates the drum 12 when thecold water valve 33 or the hot water valve 34 is open according to theoperation of the water supply apparatus 30 and water (rinsing water) issupplied to the inside the water tub 11 to make contact with the laundrysuch that the rinsing is performed by a descending force of the rinsingwater after making contact with the laundry.

In this case, the control part 72 counts the number of times duringwhich rinsing water is alternately supplied, and determines whether apredetermined fourth time, which is the time to supply the amount ofrinsing water required to lower the conductivity of the rinsing water,for example, about 7.5 seconds, is elapsed (226).

As a result of the determination in operation 226, if determined thatthe fourth time is elapsed, the control part 72 stops the alternatesupply of rinsing water (228), and measures the conductivity of therinsing water by using the conductivity sensor 18. Thereafter, themeasured conductivity is input into the control part 72 (230).

Accordingly, the control part 72 provides a feedback to the operation118 to determine whether the measured conductivity is dropped below thereference value X after the rinsing operation is performed through thestepwise supply of rinsing water in an alternate manner.

Meanwhile, as a result of the determination in operation 222, if themeasured conductivity is not greater than or equal to the fourthconductivity Y/3, the control part 72 determines that almost nodetergent remains in the rinsing water. Accordingly, the control part 72stops the rinsing cycle and provides a feedback to the operation 120 todrain the rinsing water.

In addition, the conventional rinsing cycle sets the number of times, bywhich the rinsing is performed, typically, two or three times, accordingto the weight (load) of a laundry, and proceeds with the rinsingoperation at the set number of times even if the rinsing water has asignificantly small detergent that does not require the set number oftimes of rinsing, so that the water and energy are wasted. However, therinsing cycle profile in accordance with the present disclosure does notunconditionally proceeds with the rinsing cycle up to the set number oftimes. That is, according to the rinsing profile of the presentdisclosure, if the rinsing water supplied in stages of time is measuredto be below a reference value at the first time of the rinsing cycle isperformed, the rinsing cycle is stopped at the first time withoutproceeding to the second time of the rinsing cycle.

Meanwhile, an embodiment of the present disclosure is implemented asadjusting the supply of rinsing water by counting the number of timesduring which the rinsing water is alternately supplied, but the presentdisclosure is not limited thereto. The adjusting of the supply ofrinsing water may be achieved in a manner to supply a designated waterlevel of the rinsing water using the water sensor 16 for the samepurpose and effect as the adjusting of supply of rinsing water bycounting the number of times.

In addition, the above description has been made based on the assumptionthat the laundry has a little contamination and a user manually inputs asmall amount of detergent as an example, but the present disclosure isnot limited thereto. Another example of the present disclosure may beachieved by determining the extent of contamination of laundry using theconductivity sensor 18 and automatically inputting a small amount ofdetergent for the same purpose and effect as the above example, whichwill be described with reference to FIG. 7.

FIG. 7 is a flow chart illustrating a control operation sequence of arinsing cycle of the washing machine in accordance with anotherembodiment of the present disclosure.

The following description will be made in relation to a rinsing cyclewhen the laundry has a little contamination, in which a small amount ofdetergent is automatically input through the detergent input apparatus20 other than the manual input of detergent by a user, and the rinsingprofile is changed with an optimized algorithm. In this case, thedetergent input apparatus 20 has a predetermined amount of detergentinput thereto in advance.

Referring to FIG. 7, if the user inputs the laundry having a littlecontamination, for example, bed sheet, to the inside the drum 12, andinputs the operation information, which is related to a washing course,for example, a course to wash the bed sheet and the operation of thewashing machine 1, according to the type of the laundry, the operationinformation input by the user is input into the control part 72 throughthe input part 70.

Accordingly, the control part 72 starts proceeding with the washing andrinsing according to the operation information input from the input part70.

The control part 72 detects the weight (load) of laundry that is inputto the inside the drum 12 to proceed with the washing and rinsing (300).

If the weight (load) is detected, the control part 72 sets the amount ofwashing water, the amount of rinsing water, the target RPM, the motoroperation rate (motor on-off time), and the washing time and the rinsingtime.

Thereafter, the control part 72 operates the cold water valve 33 or thehot water valve 34 to supply the water (washing water) required for thewashing cycle.

If the cold water valve 33 or the hot water valve 34 operates, the coldwater valve 33 or the hot water valve 34 is open, so that water (washingwater), which is supplied through the outside water supply pipe afterpassing through the cold water pipe 31 or the hot water pipe 32, thedetergent input apparatus 20, and the connection pipe 35, is supplied tothe inside the water tub 11 together with detergent (302).

Accordingly, the control part 72 detects a water level of the waterbeing supplied to the water tub 11 through the water level sensor 16 anddetermines whether the water level corresponds to a target washing waterlevel that is set by a designated amount of washing water, and keepssupplying until the water level of the water being supplied to the watertub 11 reaches the target washing water level.

If the supplying of washing water up to the target washing water levelis completed, the conductivity of the washing water is measured usingthe conductivity sensor 18, and the measured conductivity is input intothe control part 72 (304).

Accordingly, the control part 72 compares the measured conductivity witha reference conductivity (A: the conductivity to detect a turbidity ofthe washing water according to the extent of contamination of thelaundry, hereafter, referred to as a detergent input value), anddetermines whether the measured conductivity is below the detergentinput value A (306).

As a result of the determination in operation 306, if the measuredconductivity is below the detergent input value A, the control part 72determines that the extent of contamination of laundry is small, andautomatically inputs detergent that is less than a predetermined amountof detergent, which is set according to the weight of the laundry, tothe detergent input apparatus 20 (308). The amount of detergent beinginput to the detergent input apparatus 20, which is less than thepredetermined amount of detergent, is adjusted according to the measuredconductivity.

Meanwhile, as a result of the determination in operation 306, if themeasured conductivity is not below the detergent input value A, thecontrol part 72 determines that the extent of contamination of laundryis not small, and thus automatically inputs the predetermined amount ofdetergent that is set according to the weight of the laundry to thedetergent input apparatus 20 (310).

Thereafter, the control part 72 operates the motor 15 at thepredetermined target RPM and the predetermined operation rate (motoron-off time) that are set for the washing cycle to alternately rotatethe drum 12 such that a water current to transfer the detergent waterincluding washing water and detergent is generated, proceeding with thewashing cycle (312).

If the washing for the set washing time is completed, the control part72 stops the drum 12, drains the detergent water including washing waterand detergent (314), and proceeds with an interim spin-dry (316).

Subsequently, the control part 72 starts supplying water (rinsing water)required for the rinsing cycle. The supply of rinsing water is proceededdifferently from the supply of washing water.

Since a small amount of detergent to wash the laundry having a littlecontamination has been input through the detergent input apparatus 20,the amount of detergent remaining in the water tub 11 after the washingoperation is smaller than that remains when automatically inputting thedetergent according to the weight (load) of the laundry.

When the supply of rinsing water is started, rinsing water isalternately supplied to supply the minimum amount of rinsing waterrequired to measure the conductivity of the rinsing water (318). Thealternate supply of rinsing water is achieved as the control part 72alternately rotates the drum 12 when the cold water valve 33 or the hotwater valve 34 is open according to the operation of the water supplyapparatus 30 and water (rinsing water) is supplied to the inside thewater tub 11 to make contact with the laundry such that the rinsing isperformed by a descending force of the rinsing water after makingcontact with the laundry.

In the alternate supply of rinsing water, a first amount of water, forexample, the minimum amount of rinsing water corresponding to the weightof laundry of about 1 kg, which is required to measure the conductivityof the rinsing water, is needed to be supplied.

To this end, the control part 72 counts the number of times during whichrinsing water is alternately supplied, and determines whether apredetermined first time, which is the time to supply the minimum amountof rinsing water required to measure the conductivity of the rinsingwater, for example, about 10 seconds, is elapsed (320).

As a result of the determination in operation 320, if determined thatthe first time is elapsed, the control part 72 stops the alternatesupply of rinsing water (322), and measures the conductivity of therinsing water by using the conductivity sensor 18. The measuring of theconductivity of the rinsing water is achieved at a time when thealternate supply of rinsing water is stopped, that is, at an off-time ofthe motor operation rate (motor on-off time), and the conductivitymeasured at this time is input into the control part 72 (324).

Accordingly, the control part 72 compares the measured conductivity witha reference conductivity (X; the conductivity of having almost nodetergent in the rinsing water, the conductivity having a level of about250 μs/cm, hereinafter, referred to as a reference value), anddetermines whether the measured conductivity is below the referencevalue X (326).

As a result of the determination in operation 326, if determined thatthe measured conductivity is below the reference value X, the controlpart 72 determines that almost no detergent remains in the rinsingwater, and thus drains the rinsing water without proceeding with therinsing cycle (328).

After the rinsing water is drained, the control part 72 performs aspin-dry cycle at a predetermined final spin-dry RPM, about 1100 RPM orabove (330), and stops the drum 12, completing all cycles.

As described above, the conductivity of the rinsing water is measuredduring the rinsing cycle, and if the measured conductivity is below thereference value X, the rinsing cycle is finished, and then enters to thefinal spin-dry cycle, so that the rinsing operation is achieved with theoptimum algorithm without wasting the water and the energy.

As a result of the determination in operation 326, the measuredconductivity is not below the reference value X, the control part 72determines that detergent remains in the rinsing water, and proceedswith the operation 200 in FIG. 6, for a rinsing profile to control theamount of rinsing water and the rinsing time while supplying the rinsingwater in stages according to the measured conductivity. Since the higherthe conductivity detected by the conductivity sensor 18 is, the moredetergent remains in the rinsing water, the rinsing profile is to adjustthe amount of rinsing water, which is to be supplied at a next stage oftime, to reduce the rinsing time while saving the amount of rinsingwater.

Although a few embodiments of the present disclosure have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the disclosure, the scope of which is definedin the claims and their equivalents.

What is claimed is:
 1. A method of controlling a washing machineprovided with a drum, a water tub installed outside the drum to receiverinsing water and a motor to rotate the drum, the method comprising:supplying rinsing water in a stepwise manner; performing a rinsing cycleby alternately rotating the drum according to a drive of the motorduring the supplying of rinsing water in a stepwise manner; measuring aconductivity of the rinsing water during the performing of the rinsingcycle; and changing a rinsing profile of the rinsing cycle according tothe measured conductivity of the rinsing water.
 2. The method of claim1, wherein the supplying of rinsing water in a stepwise mannercomprises: supplying the rinsing water for a first time that is set tomeasure the conductivity of the rinsing water; and supplying the rinsingwater for a time that is set in stages to adjust an amount of supply ofthe rinsing water according to the measured conductivity.
 3. The methodof claim 2, wherein the first time is a time configured to supply aminimum amount of rinsing water required to measure the conductivity ofthe rinsing water.
 4. The method of claim 2, wherein the time set instages is a time configured to supply an amount of rinsing watersuitable to adjust the amount of supply of the rinsing water.
 5. Themethod of claim 2, wherein the amount of supply of the rinsing water isadjusted to be in proportion to the measured conductivity.
 6. The methodof claim 5, wherein if the conductivity is large, the amount of supplyof the rinsing water is increased so that the conductivity of therinsing water is rapidly lowered.
 7. The method of claim 1, wherein therinsing cycle performs an alternate supply of water in which the drum isalternately rotated whenever the rinsing water is supplied in a stepwisemanner.
 8. The method of claim 7, wherein in the measuring of theconductivity of the rinsing water, the conductivity of the rinsing wateris measured when the alternate supply of water is stopped.
 9. The methodof claim 8, wherein the rinsing profile compares the measuredconductivity of the rinsing water with a reference value, and finishesthe rinsing cycle that is performed through the alternate supply ofwater if the measured conductivity is below the reference value.
 10. Themethod of claim 8, wherein the rinsing profile compares the measuredconductivity of the rinsing water with a reference value, and controlsthe rinsing cycle that is performed through the alternate supply ofwater if the measured conductivity is greater than or equal to thereference value.
 11. The method of claim 10, wherein in the rinsingcycle performed through the alternate supply of water, rinsing water issupplied while adjusting the amount of supply of rinsing water accordingto the measured conductivity, and an alternate supply of water isperformed in which the drum is alternately rotated when the rinsingwater is supplied.
 12. The method of claim 11, wherein the amount ofsupply of the rinsing water is adjusted by supplying rinsing water forthe time that is set according to the measured conductivity.
 13. Themethod of claim 12, wherein if the measured conductivity is higher, thetime set to supply rinsing water is larger such that a larger amount ofthe rinsing water is supplied.
 14. The method of claim 11, wherein theamount of supply of the rinsing water is adjusted by supplying rinsingwater to a water level that is set according to the measuredconductivity.
 15. The method of claim 14, wherein if the measuredconductivity is higher, the water level set to supply rinsing water islarger such that a larger amount of the rinsing water is supplied.
 16. Awashing machine comprising: a water tub; a water supply apparatusconfigured to supply the water tub with rinsing water; a conductivitysensor configured to measure a conductivity of the rinsing water; and acontrol part, at a rinsing cycle, configured to supply the water tubwith the rinsing water in a stepwise manner by controlling the watersupply apparatus, and to change a rinsing profile of the rinsing cycleaccording to the conductivity of the rinsing water that is measured bythe conductivity sensor.
 17. The washing machine of claim 16, whereinthe water supply apparatus supplies the rinsing water in a stepwisemanner according to a control of the control part, wherein the watersupply apparatus supplies the rinsing water for a first time that is setin the control part so as to measure the conductivity of the rinsingwater, and supplies the rinsing water for a time that is set in stagesin the control part so as to adjust an amount of supply of the rinsingwater according to the measured conductivity.
 18. The washing machine ofclaim 17, wherein the control part adjusts the amount of supply of therinsing water that is to be in proportion to the measured conductivity.19. The washing machine of claim 18, wherein the control part controls,if the conductivity is large, the amount of supply of the rinsing wateris increased so that the conductivity of the rinsing water is rapidlylowered.
 20. The washing machine of claim 16, further comprising a motorto rotate the drum, wherein the control part performs the rinsing cycleby alternately rotating the drum according to the driving of the motorduring the supplying of water in a stepwise manner.
 21. The washingmachine of claim 20, wherein the conductivity sensor measures aconductivity of the rinsing water that is changed through the alternatesupply of water.
 22. The washing machine of claim 21, wherein thecontrol part compares the measured conductivity of the rinsing waterwith a reference value, and if the measured conductivity is below thereference value, changes the rinsing profile to finish the rinsing cyclethat is performed through the alternate supply of water.
 23. The washingmachine of claim 21, wherein the control part compares the measuredconductivity of the rinsing water with a reference value, and if themeasured conductivity is greater than or equal to the reference value,changes the rinsing profile to control the rinsing cycle that isperformed through the alternate supply of water.
 24. The washing machineof claim 23, wherein the control part controls the water supplyapparatus to adjust an amount of supply of the rinsing water accordingto the measured conductivity.
 25. The washing machine of claim 24,wherein the control part controls to adjust an amount of supply of therinsing water during a time that is set according to the measuredconductivity.
 26. The washing machine of claim 25, wherein if themeasured conductivity is higher, the control part controls the time,which is set to supply the rinsing water, to be larger such that alarger amount of the rinsing water is supplied.
 27. The washing machineof claim 24, wherein the control part adjusts the amount of supply ofthe rinsing water to a water level that is set according to the measuredconductivity.
 28. The washing machine of claim 27, wherein if themeasured conductivity is higher, the water level is set to be largersuch that a larger amount of the rinsing water is supplied.